Complex compounds which contain the trisodium salt of m-trisulfonated triphenylphosphane of the chemical formula P(C.sub.6 H.sub.4 -m-SO.sub.3 Na).sub.3 as the only ligand or as one of several ligands, are little known. DE 27 00 904 C2, Example 12, describes the reaction of bis (1,5-cyclooctadiene)nickel with the trisodium salt of tris(m-sulfophenyl)phosphane (hereinafter TPPTS). A red compound is obtained which is recovered as a solid substance from its aqueous solution by evaporation in a vacuum. The Inventors claim that this compound is the tetrakis-tri-sodium salt of tris[m-sulfophenyl)phosphanelnickel(O).
In the same publication, there is also general information on the preparation of TPPTS complex compounds of iron and palladium. Water-soluble compounds, or those compounds which dissolve under the reaction conditions, are reacted with aqueous TPPTS solution in the presence of a reducing agent, e.g. Na[BH.sub.4 ], K[BH.sub.4 ], zinc powder, magnesium, or boron hydrides. Neither the preparation process nor the individual compounds are described in further detail through examples or even characterized.
Complex compounds containing TPPTS as a ligand, without the exact composition of these compounds being known, are formed from metal or metal compounds, TPPTS and optionally other ligands in various reactions. Thus, rhodium complexes with TPPTS ligands have recently gained special significance as components of catalyst systems which are used in the hydroformylation of olefins. Compared with other catalysts which are used for the same reaction, they have the advantage of being soluble in water. Therefore, the hydroformylation can be performed in a heterogeneous reaction medium consisting of aqueous and organic phases (two-phase system), with the result that the reaction product can then be separated from the water-soluble catalyst by simple phase separation. Furthermore, this procedure ensures that the valuable noble metal catalyst can be recovered with almost no loss, or recycled to the synthesis stage. Such a process is described, for example, in the DE 26 27 354 B2.
The addition of hydrogen cyanide to unsaturated organic compounds can also be performed in the presence of a compound of zero-valent nickel or iron or palladium of reduced valency and an aqueous solution of a sulfonated triphenylphosphane, in particular an aqueous solution of TPPTS, as a catalyst. This procedure is described in the DE 27 00 904 C2 previously cited. Instead of the nickel salt and TPPTS solution, a specially prepared complex compound, to which the composition Ni(TPPTS).sub.4 is ascribed, can also be used as the catalyst.
In spite of the afore-mentioned advantages of using water-soluble TPPTS complex compounds as catalysts, nothing is known about their use in other reactions.
This situation is probably largely due to the fact that, despite intensive efforts, it has so far not been possible to isolate TPPTS-containing, water-soluble complex compounds in pure form and thus to permit their substance characterization by chemical and physical analytical processes.
The problem to be solved by the present invention was, therefore, to prepare TPPTS-containing complex compounds of certain metals, said compounds having a definite reproducible composition.